It would be nice to be able to see a report for user locale/language. In countries like Switzerland there are multiple relevant languages so the Location report doesn’t help that much.
Currently it’s possible to get user language stats manually by attaching a custom property with a pageview but a default report would be nice too.
English language
I live in Switzerland with it’s 3 (4!) official languages and having visits shown as coming from “Switzerland” is not as useful as showing what is the language of my visitors would be.